One hour of rolling is exhausting. I rolled for 17 minutes with another blue belt without a tap and had a hard time standing afterward. same with a competition match I had, went only 7 minutes, but it was 150%
No joke. There has been a couple of time when I was lucky enough to have the mat to myself with a buddy. We were pretty evenly matched and we rolled continuously (without a single tap out) for almost an hour. It was exhausting... cause my buddy was going hard for most of that hour.